The broad objective of this research is to gain basic knowledge about the processes involved in the discrimination (or detection) of changes in one's own blood pressure. Male and female subjects, including normotensives and mild hypertensives, are studied under different experimental conditions. The basic questions of the research are: (1) To what extent can normal and hypertensive subjects detect variations in their own blood pressure? (2) To what extent is this ability improved by discrimination training (knowledge of results)? (3) To what extent is the discrimination performance of subjects specific to the function for which discrimination training is provided? (4) How does discrimination performance change as a function of stress-induced elevations in pressure? (5) How does discrimination performance relate to voluntary control of blood pressure? (6) How does discrimination performance relate to other selected physiological and psychological factors? The experiments are conducted under computer control. Continuous recordings are made of systolic and diastolic pressure (using a tracking-cuff system), heart rate, respiration and other physiological variables. Blood pressure discrimination is related to changes in the other physiological variables and to various subjective data obtained from post-experimental questionnaires. The research will help us understand that internal sensations and physiological processes are associated with blood pressure variability and discrimination. The research has potential application to the non-pharmacologic management of hypertension.